fun readStr () =
    let
        fun scan reader stream = SOME (StringCvt.splitl (not o Char.isSpace) reader (StringCvt.skipWS reader stream))
    in
        valOf (TextIO.scanStream scan TextIO.stdIn)
    end


val () =
    let
        val s1 = readStr ()
        val s2 = readStr ()
        val s3 = readStr ()

        fun findAns () =
            let
                exception BadInput

                fun findAnsAux [] = 0
                  | findAnsAux ("RED" :: tl) = 1 + findAnsAux tl
                  | findAnsAux ("BLUE" :: tl) = ~1 + findAnsAux tl
                  | findAnsAux _ = raise BadInput 
            in
                if 0 < findAnsAux [s1, s2, s3] then "RED"
                else "BLUE"
            end
                        
        val ans = findAns ()
    in
        print (ans ^ "\n")
    end